Joshua 7 is the record of the first battle for the city of Ai and the sin of Achan. Immediately after the successful battle for the city of Jericho, the Lord's people were to go up against the city of Ai. According to scouts the city would be easy to take and only two or three thousand soldiers would be needed. About three thousand men attacked the city, but they were driven back and 36 Israelites were smitten. When Joshua took this problem to God, he was told that "Israel hath sinned; therefore the children of Israel could not stand before their enemies (Jos. 7:11 & 12) The people were questioned and Achan confessed that he kept for himself some of the loot taken in battle. This, Achan knew, was contrary to the word of the Lord. Because of his sin, Achan was stoned and he and his property were burned thus removing the sin within Israel. Chapter 8 then gives the account of the second battle for Ai in which victorious Israel utterly destroyed the city.
The example clearly teaches that we are not to tolerate sin within our ranks. Some would say that sin is an individual thing and it only affects the individual sinner, but notice what happened. Because of the individual sin the army of the Lord could not be successful and w. as beaten. Because of the individual sin 36 Israelites lost their lives. It is true that only Achan had to answer for his sin and only he was punished, but the consequences of his act had a devastating effect on all of Israel. Without ridding themselves of this guilt the Israelites could not continue with the conquest of the promised land.
Today the same principle would still apply. If we have sin within, the army of the Lord cannot make progress. The people of God will be weak and unable to win their battles. It is true that some will remain loyal to the Lord and not lose their souls, but many will be lost to the world just as 36 good men were lost at Ai. We must be alert and root out any sin that is among us so that the glorious army of the Lord will not be hampered in its battle. We truly are in a desperate war to wan from the world the souls of men and more importantly to retain those souls. - James Finley